1. Deprit, A.: 1969,Celest. Mech. 1, 12.
2. Feng, K.: 1985,Proc. 1984 Beijing Symp. on Diff. Geometry and Diff. Eq., ed. by K. Feng, Science Press, Beijing, p. 42.
3. Feng, K.: 1993,Proc. 1st China-Japan Conf. on Numer. Math., eds, Z. C. Shi and T. Ushijima, World Scientific, Singapore, p. 1.
4. Kinoshita, H., et al.: 1991,Celest. Mech. 52, 59.
5. Liao, X. H. and Liu, L.: 1993,Acta Astron. Sinica 34, 198.